1. Field of Invention
This invention relates to article moving means and more particularly to such means incorporating vacuum to aid in article movement.
2. Description of the Prior Art
In the movement of sheet materials it is known to utilize vacuum pads or vacuum cups on the end of articulated arms to lift a particular item from a stack of similar items for purposes of singulating the items. Such apparatus is commonly found in printing as adjuncts to printing presses where successive blank sheets of paper are lifted off a stack of papers by a vacuum device and passed through the press.
A problem occurs when the items to be singulated are of unequal size from one to the next. In that situation the design of a vacuum pad that works with all contemplated sizes of items is very difficult. If the pad is small enough not to extend off the edges of the smallest item it may be inadequate in the amount of vacuum to lift the largest item off the stack. Conversely if the vacuum pad is made large enough to lift even the largest item off a stack it may be so large as to lift off items beneath a small item in the stack.